Compositions containing styrenic polymers such as ABS are widely used owing to the high impact strength, tensile strength and hardness and the thermoplastic properties of styrenic polymers. However, many compositions containing styrenic polymers exhibit relatively slow electrostatic charge dissipation rates which make the compositions unacceptable for uses wherein rapid dissipation of static electrical charges is required.
Various means have been developed for reducing electrostatic charge retention in polymer compositions. According to one method, an article molded from a polymer composition may be coated with an antistatic film coating material. According to another method, static charge retention in a polymer composition may be reduced by incorporating a material having antistatic properties into the polymer composition For example, the Puletti et al U.S. Pat. No. 3,425,981 discloses polymer compositions including homopolymers and copolymers of ethylene oxide to reduce static charge retention and the Ebneth et al U.S. Pat. No. 3,450,794 discloses polymer compositions including polypropylene glycol. The Tanaka et al U.S. Pat. No. 4,543,390 discloses antistatic polymer compositions including super fine particle polymers comprising graft copolymers of polyalkylene oxide and at least one vinyl monomer.
The Federl et al U.S. Pat. No. 4,588,773 discloses an improved antistatic polymer composition comprising less than 80% by weight of an ABS graft copolymer and more than 20% by weight of an epihalohydrin copolymer. The polymer compositions disclosed by Federl et al exhibit charged decay rates from 5,000 volts to 0 volts of less than about 2 seconds. The ability of these compositions to rapidly dissipate static electrical charge makes these polymer compositions particularly advantageous for use in many applications. However, Applicants have discovered that the delamination tendencies and low tensile elongation properties of the polymer compositions disclosed by Federl et al are somewhat inferior to other polymer compositions containing ABS polymers, therefore limiting the use of these compositions in various applications.
It is therefore an object of the present invention to provide polymer blend compositions which exhibit good antistatic properties with reduced delamination and improved ductility as indicated by tensile elongation. Specifically, it is an object of the present invention to provide polymer blend compositions which exhibit rapid dissipation of static electrical charges and improved ductility and reduced delamination tendencies exhibited by increased tensile elongation before breaking.